Wagner attended Colony High School in Ontario, California, US. In 2008, he registered 125 tackles (92 solo, 33 assists), including four sacks as a senior. Also played tight end, tallying 37 catches for 595 yards with 11 touchdowns. He received all-CIF Central Division honors as well as all-Mount Baldy League accolades. Earned second-team California Division 2 all-state honors after helping lead the Titans to a CIF division title and was named to the all-San Bernardino County team.

Wagner was considered one of the best linebacker prospects in his class. At the 2012 NFL Draft, Wagner was selected in round 2, pick 47 by the Seattle Seahawks. He is the highest selected player from Utah State since Rulon Jones in 1980. Bobby Wagner finished his rookie season with 140 tackles, 2 sacks, and 3 interceptions. After his rookie year with the Seahawks, he was ranked as the #1 rookie inside linebacker, and second in the position in the entire league, by ProFootballFocus. Wagner finished his second season with 120 tackles, 5 sacks with a interception. Wagner helped lead the Seahawks to a 43-8 win over the Denver Broncos in Super Bowl XLVIII. In his 3rd season Bobby Wagner had an impressive season with 5 games with more than 10 tackles. Even though he missed 5 games, however he was able to be voted into the Pro Bowl marking his first pro bowl of his career.